Wireless device, an access point and respective methods performed thereby for communicating with the other

ABSTRACT

An Access Point (AP) and a wireless device, as well as complementary methods performed by the AP and the wireless device for communication with each other, are provided. Embodiments of the AP-performed method can include determining one or more Clear Channel Assessment Thresholds (CCATs) for data to be transmitted to the wireless device, wherein each CCAT is associated with a particular Quality of Service (QoS) category of the data. Such embodiments can also include determining whether the channel is busy or free based on the determined one or more CCATs and based on signals or energy detected on the channel and, based on determining that the channel is free, transmitting the data to the wireless device. In some embodiments, the data can be transmitted to the wireless device while further data is being transmitted on the channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims the benefit ofpriority from, U.S. patent application Ser. No. 15/572,237 filed on Nov.7, 2017, which is a U.S. national-stage application claiming priority tointernational application PCT/SE2015/050636 filed on Jun. 1, 2015. Theentire disclosures of the above-mentioned applications are incorporatedherein by reference for all purposes.

TECHNICAL FIELD

The present disclosure relates to wireless communication and inparticular to communication between an Access Point, AP, and a wirelessdevice.

BACKGROUND

In Institute of Electrical and Electronics Engineers, IEEE, Wi-Fi (alsoknown as Wireless Local Area Network, WLAN, and these terms will be usedinterchangeably throughout this document) is standardised in the 802.11specifications (IEEE Standard for Informationtechnology—Tele-communications and information exchange between systems.Local and metropolitan area networks—Specific requirements. Part 11:Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)Specifications). Wi-Fi is a technology that currently mainly operates onthe 2.4 GHz or the 5 GHz band. The IEEE 802.11 specifications regulatethe access points' or wireless terminals' physical layer, MAC layer andother aspects to secure compatibility and inter-operability betweenaccess points and portable terminals. Wi-Fi is generally operated inunlicensed bands, and as such, communication over Wi-Fi may be subjectto interference sources from any number of both known and unknowndevices. Wi-Fi is commonly used as wireless extensions to fixedbroadband access, e.g. in domestic environments and hotspots, likeairports, train stations and restaurants.

The WLAN technology relies on Carrier Sensing Multiple Access withCollision Avoidance, CSMA/CA, in order to effectively and fairly sharethe wireless medium among different WLAN entities and even differentRadio Access Technologies, RAT. CSMA/CA applied by the WLAN systemdemands that every device that wishes to send data senses the commoncommunication channel before carrying a transmission in order to avoidduplicate transmissions (usually resulting in loss of data and need ofretransmissions). In order for a device to deem the channel busy, it hasto detect a transmission, the received signal strength level of whichsurpasses a pre-determined threshold, referred to as the Clear ChannelAssessment, CCA, threshold, CCAT.

A problem may be that an AP or wireless device may refrain fromaccessing the medium since it is exposed to concurrent transmissions inneighbouring Basic Service Sets, BSSs, although simultaneouscommunication would be possible. This limits the performance of currentsystems, especially as the CCA threshold used today is very low, −82dBm.

In the past, WLANs were mainly used to transport low-bandwidth,data-application traffic. Currently, with the expansion of WLANs intovertical (such as retail, finance, and education) and enterpriseenvironments, WLANs are used to transport high-bandwidth dataapplications, in conjunction with time-sensitive multimediaapplications. Consequently, the load of the WLANs has increasedsubstantially during the last years and is likely to increase evenfurther. With increased traffic, denser WLANs, the interference mayincrease and it may reduce the probability of an AP and/or a wirelessdevice to swiftly access a channel or radio resources of the WLAN.

SUMMARY

The object is to obviate at least some of the problems outlined above.In particular, it is an object to provide an AP, a wireless device andrespective methods performed thereby for communicating with each other.These objects and others may be obtained by providing an AP and awireless device as well as a method performed by an AP and a methodperformed by a wireless device according to the independent claimsattached below.

According to an aspect a method performed by an AP in a WLAN forcommunicating with a wireless device is provided. The WLAN employscontention based access for radio resources. The method comprises usinga first CCAT for a first Quality of Service, QoS, category and at leasta second CCAT for a second QoS category for communication with thewireless device.

According to an aspect, a method performed by a wireless device forcommunicating with an AP is provided. The WLAN employs contention basedaccess for radio resources. The method comprises determining a CCAT fora QoS category of data to be transmitted to the AP, wherein at least twodifferent QoS categories are associated with different CCATs;determining whether the channel is busy or free using the determinedCCAT: and transmitting data to the AP when the channel is determined tobe free.

According to another aspect, an AP in a WLAN for communicating with awireless device is provided. The WLAN employs contention based accessfor radio resources. The AP is configured for using a first CCAT for afirst QoS category and at least a second CCAT for a second QoS categoryfor communication with the wireless device.

According to yet another aspect, a wireless device in a WLAN forcommunicating with an AP is provided. The WLAN employs contention basedaccess for radio resources. The wireless device is configured fordetermining, a CCAT for a QoS category of data to be transmitted to theAP, wherein at least two different QoS categories are associated withdifferent CCATs; for determining whether the channel is busy or freeusing the determined CCAT; and for transmitting data to the AP when thechannel is determined to be free.

The method performed by the AP and the method performed by the wirelessdevice as well as the AP and the wireless device may have severaladvantages. One possible advantage is that the flexibility of the QoSframework is improved and/or increased by introducing another degree offreedom to the parameters that can be adjusted in order to providestatistical differentiation between different traffic types.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments will now be described in more detail in relation to theaccompanying drawings, in which:

FIG. 1A is a flowchart of a method performed by an AP operable in a WLANfor communicating with a wireless device according to an exemplifyingembodiment.

FIG. 1B is a flowchart of a method performed by an AP operable in a WLANfor communicating with a wireless device according to anotherexemplifying embodiment.

FIG. 1C is a flowchart of a method performed by an AP operable in a WLANfor communicating with a wireless device according to yet anotherexemplifying embodiment.

FIG. 2A is a flowchart of a method performed by a wireless deviceoperable in a WLAN for communicating with an AP according to anexemplifying embodiment.

FIG. 2B is a flowchart of a method performed by a wireless deviceoperable in a WLAN for communicating with an AP according to anotherexemplifying embodiment.

FIG. 3A is a schematic illustration of a relation between the spatialarea from where transmitting nodes will cause the AP to consider thechannel as being busy and the CCAT.

FIG. 3B is an exemplifying illustration of channel access prioritiesincluding Enhanced Distributed Channel Access, EDCA, with associatedtiming.

FIG. 3C is an exemplifying illustration of the EDCA parameter setelement with example values.

FIG. 3D is an exemplifying illustration of the CCAT and the EDCAparameter set element with example values.

FIG. 3E is an exemplifying illustration of CCAT per transmitting andsensed traffic access category combination with example values.

FIG. 4 is a block diagram of an AP operable in a WLAN for communicatingwith a wireless device according to an exemplifying embodiment.

FIG. 5 is a block diagram of an AP operable in a WLAN for communicatingwith a wireless device according to another exemplifying embodiment.

FIG. 6 is a block diagram of a wireless device operable in a WLAN forcommunicating with an AP according to an exemplifying embodiment.

FIG. 7 is a block diagram of a wireless device operable in a WLAN forcommunicating with an AP according to another exemplifying embodiment.

FIG. 8 a block diagram of an arrangement in an AP operable in a WLAN forcommunicating with a wireless device according to an exemplifyingembodiment.

FIG. 9 is a block diagram of an arrangement in a wireless deviceoperable in a WLAN for communicating with an AP according to anotherexemplifying embodiment.

DETAILED DESCRIPTION

Briefly described, an AP and a wireless device as well as a methodperformed by the AP and a method performed by the wireless device forcommunication with the other are provided. The AP and the wirelessdevice are operable in a WLAN employing contention based access forradio resources. When the AP or wireless device senses the channel, orradio resources, in order to determine if the channel is busy or free,the AP and the wireless device uses different CCATs depending on the QoScategory of the data that the AP or the wireless device is to send tothe receiving party.

Embodiments herein relate to a method performed by an Access Point, AP,operable in a WLAN for communicating with a wireless device, the WLANemploying contention based access for radio resources.

Embodiments of such a method will now be described with reference toFIGS. 1A-1C. FIG. 1A illustrates the method comprising using 130 a firstClear Channel Assessment Threshold, CCAT for a first Quality of Service,QoS, category and at least a second CCAT for a second QoS category forcommunication with the wireless device.

Different types of data that is to be transmitted by the AP may beassociated with different QoS categories. Merely as a non-limitingexample, some data may be very time critical and some data may not betime critical. Different services, such as voice, video, file transferetc. may be associated with different QoS or QoS categories.

Different QoS categories are associated with a respective CCAT, suchthat a first QoS category is associated with a first CCAT, a second QoScategory is associated with a second CCAT, a third QoS category isassociated with a third CCAT, and so on. There is at least two differentCCATs, hence there is at least two predefined QoS categories. There maybe more QoS categories than there are CCATs as some QoS categories maybe assigned or associated with the same CCAT. Hence, there is at least aCCAT associated with a first QoS category, and a second CCAT associatedwith a second QoS category.

When the AP communicates with the wireless device, e.g. transmits datato the wireless device, the AP ascertains that the channel, or radioresources, are free to be used for the transmission to the wirelessdevice. Depending on the QoS category of the data that the AP is totransmit to the wireless device, the AP uses the corresponding CCAT whensensing the channel and ascertaining that the channel is free or busy.

Thus, when the AP is to transmit data of the first QoS category, the APuses the first CCAT when sensing the channel and ascertaining that thechannel is free or busy; and when the AP is to transmit data of thesecond QoS category, the AP uses the second CCAT when sensing thechannel and ascertaining that the channel is free or busy.

It shall be noted that FIG. 1A illustrates also a box 110 and a box 120,both having dotted lines to illustrate that they are not compulsory tothis embodiment as will be explained below.

The method performed by the AP may have several advantages. One possibleadvantage is that the flexibility of the QoS framework is improvedand/or increased by introducing another degree of freedom to theparameters that can be adjusted in order to provide statisticaldifferentiation between different traffic types.

The method may further comprise determining 110 the first CCAT and/orthe second CCAT for the first and second QoS category.

The different CCATs for the individual QoS categories, i.e. at leastfirst CCAT of the first QoS category and the second CCAT of the secondQoS category may be determined by the AP based on different information.For example, transmission traffic type, sensed traffic type or acombination thereof may be used as a base to determine the differentCCATs for the individual QoS categories.

Alternatively, the different CCATs for the individual QoS categories maybe predefined; or they may be determined by higher layers, e.g. anOperation, Administration and Maintenance, OAM, system or OperationSupport System, OSS, and then signalled to the AP.

It shall be pointed out that the AP may determine a first and secondCCAT for the first and second QoS category respectively to use foritself and another first and second CCAT for the first and second QoScategory respectively to be used by the wireless device.

Still further, the method may comprise transmitting 120 the first CCATand/or the second CCAT for the first and second QoS category to thewireless device.

In the cases that (i) the AP determines the different CCATs for theindividual QoS categories, i.e. the first CCAT for the first QoScategory and at least the second CCAT for the second QoS category, or(ii) the CCATs are determined by higher layers and signalled to the AP,the AP has to inform the wireless device in case the wireless devicealso has the use the different CCATs for different QoS categories ofdata that the wireless device wants to transmit to the AP. This will beexplained in more detail below.

In the case that the different CCATs are predefined, the wireless devicemay already have this information hardcoded into a memory of thewireless device and then there is no need for the AP to transmit thefirst and at least the second CCAT for the first and at least the secondQoS category.

Further as described above, the AP may determine a first set of firstand second CCATs for the first and second QoS category respectively foritself and a second set of first and second CCATs for the first andsecond QoS category respectively for the wireless device. If so, thenthe AP transmits the second set of first and second CCATs for the firstand second QoS category respectively for the wireless device to thewireless device.

In an example, the determining 110 of the first and/or second CCATcomprises determining respective intervals for the first and secondCCATs within which the first and the second CCATs may vary.

By determining respective intervals for the first and second CCATswithin which the first and the second CCATs may vary, the AP (and alsothe wireless device) may have the liberty to adapt the CCAT based on aspecific mechanism, e.g. setting the CCAT based on the measured ReceivedSignal Strength, RSS, from the wireless device (for the AP), or from theAP (for the wireless device). Another example may be that theAP/wireless device adjusts the CCAT based on the fraction of failedpackets (Block Error Rate, BLER).

The method may further comprise, as illustrated in FIG. 1B, when using130 the determined first and/or second CCAT for communication with thewireless device, determining 140 whether the channel is busy or freeusing the CCAT for the QoS category of the data to be transmitted to thewireless device; and transmitting 150 data to the wireless device whenthe channel is free.

When the AP senses the channel, it may detect, or receive, signals orenergy on the channel, or the radio resources of the channel. Thesignals/energy may be of different strengths, or energy levels.

In order to determine, or ascertain, whether the channel is busy orfree, the AP compares the detected/received signals/energy to the CCATassociated with the QoS category of the data to be transmitted to thewireless device.

For example, if the data to be transmitted to the wireless device has arelatively high priority meaning that the QoS category is of relativelyhigh priority, the CCAT for that QoS category may be lower than the CCATfor a QoS of relatively low priority. In this manner, it may be moreprobable that the AP finds the channel free using a lower CCAT thanusing a higher CCAT. Consequently, if the data to be sent to thewireless device has high priority, it may be more probable that the APfinds the channel free than if the data to be sent to the wirelessdevice has low priority.

The determining 140 of whether the channel is busy or free may furtherbe based on a QoS category of data that is currently being transmittedon the channel as discovered during the determining 140 of whether thechannel is busy or free.

The AP may receive packets or signals currently being transmitted on thechannel when the AP senses the channel in order to determine if thechannel is free or busy. The AP may then decode the packets/signals,perform some analysis of the packet or perform deep packet inspection inorder to determine the QoS category of data that is currently beingtransmitted on the channel.

Using the obtained information about the QoS category of data that iscurrently being transmitted on the channel, the AP may determine if thechannel is busy or free. Thus, not only is the CCAT for the QoS categoryof the data to be transmitted used to determine whether the channel isfree or busy, but also the QoS category of data that is currently beingtransmitted on the channel.

By using both the QoS category for the data that is to be transmittedand the QoS category of data that is currently being transmitted on thechannel, the AP may make a more well-founded decision of whether thechannel is busy or free.

In an example, the channel is determined to be free if the level of theQoS category of the data to be transmitted to the wireless device is ofhigher priority than the level of the QoS category of data that iscurrently being transmitted on the channel.

By using the different QoS categories of the data to be transmitted tothe wireless device and the QoS category of data that is currently beingtransmitted on the channel, the AP may ascertain that when it has highpriority data that is to be transmitted, i.e. data of a QoS categoryhaving a high priority level, the probability that this data will besent with a minimum of delay may be relatively high.

Comparing the priority level of the different QoS categories may helpthe AP to increase the probability that the data of the QoS category ofa high priority level will be sent in time. Assuming the AP detectstraffic on the channel using the CCAT for the data of its QoS categorywhich is of a high priority level. The AP may inspect, analyse, ordecode the detected traffic in order to determine its QoS category. Evenif the AP detects traffic on the channel, it does not automaticallyrefrain from transmitting its data to the wireless device. Rather, ifthe priority level of the QoS category of the detected traffic is lowerthan the priority level of the QoS category of the data to betransmitted to the wireless device, the AP may determine that thechannel is free and transmit the data to the wireless device.

By increasing the CCAT for a certain QoS category, the traffic of thataccess class has increased probability of accessing the channel, but itcomes at a risk of suffering from interference. Therefore the CCAT maye.g. only be increased for traffic types that are not sensitive tolosing packets (e.g. it may not be suitable for voice and video butrather for best effort or background).

The respective QoS categories may be associated with Access Categories.

There are four different QoS differentiations in the IEEE 802.11-2012standard, referred to as access categories. These categories are Voice(VO), Video (VI), Best Effort (BE) and Background (BK). The methodperformed by the AP may be employed by an AP operable in a network basedon the IEEE 802.11 standard, wherein these already defined accesscategories may be used. However, it shall be pointed out that the accesscategories may be defined in other ways, e.g. when the AP is operable ina network based on another standard.

The method may further comprise, as illustrated in FIG. 1C, updating 160at least one of the CCATs and transmitting 170 the updated at least oneCCAT to the wireless device.

It may be that different circumstances change requiring that at leastone of the CCATs may need to be updated. There may be several reasonswhy at least one CCAT may need to be updated, e.g. due to informationdeduced from statistics that has been collected by the AP or a higherlay node in the network, e.g. an AP controller, an OAM node or an OSSnode. Merely as an example, if a CCAT for a specific QoS categoryresults in high failure rates or long delays, the CCAT for that specificQoS category may have to be decreased.

Once a CCAT has been updated, the AP transmits the updated CCAT to thewireless device such that the wireless device may use the updated CCATfor communication with the AP.

The determined first and/or second CCAT may be (i) specific for thewireless device, or (ii) common for all wireless devices communicatingwith the AP.

There may be a plurality of wireless devices located within a coveragearea of the AP, which is generally referred to as a Basic Service Set,BSS. Different wireless devices may be associated with differentpriorities, some having higher priority than others. In such a scenario,a first wireless device associated with higher priority may be assigneda first set of CCATs that are different from a second set of CCATs thatare assigned to a second wireless device associated with lower priority.The first set of CCATs may be selected such that it increases theprobability for the first wireless device to access the channel comparedto the second wireless device.

In the other alternative, all wireless devices may be associated withthe same set of CCATs, wherein the CCATs of the set are associated withdifferent QoS categories as described above.

Embodiments herein also relate to a method performed by a wirelessdevice in a WLAN for communicating with an AP, the WLAN employingcontention based access of a channel to the AP.

Embodiments of such a method will now be described with reference toFIGS. 2A-2B. FIG. 2A illustrates the method comprising determining 220 aCCAT for a QoS category of data to be transmitted to the AP, wherein atleast two different QoS categories are associated with different CCATs;determining 230 whether the channel is busy or free using the determinedCCAT: and transmitting 240 data to the AP when the channel is determinedto be free.

The wireless device has data to send to the AP. The data is associatedwith a QoS category. Different QoS categories are associated with arespective CCAT, such that a first QoS category is associated with afirst CCAT, a second QoS category is associated with a second CCAT, athird QoS category is associated with a third CCAT, and so on. There isat least two different CCATs, hence there is at least two predefined QoScategories. There may be more QoS categories than there are CCATs assome QoS categories may be assigned or associated with the same CCAT.Hence, there is at least a CCAT associated with a first QoS category,and a second CCAT associated with a second QoS category.

Consequently, the wireless device determines the CCAT for the QoScategory of data to be transmitted to the AP. The wireless device thenuses the CCAT for determining whether the channel is busy or free. Thechannel is determined free if any detected or received signal or energyis below the CCAT. Similarly, the channel is determined busy if anydetected or received signal or energy is above the CCAT. The CCAT beingspecific for the QoS category of the data that the wireless device is totransmit to the AP.

In the above described manner, the channel is determined busy or freeusing the specific CCAT for the QoS category of the data that thewireless device is to transmit to the AP. When the channel is determinedto be free, the wireless device transmits the data to the AP.

The method performed by the wireless device may have the same severaladvantages as the method performed by the AP. One possible advantage isthat the flexibility of the QoS framework is improved and/or increasedby introducing another degree of freedom to the parameters that can beadjusted in order to provide statistical differentiation betweendifferent traffic types.

The method may further comprise, as illustrated in FIG. 2B, receiving210, from the AP, a first CCAT for a first QoS category and at least asecond CCAT for a second QoS category, whereby the first and second CCATare different.

The first and the second, and possible further, CCATs may be predefinedor they may be determined by the AP or a node in the wireless network.In case the CCATs are determined by the AP or a node in the wirelessnetwork, the wireless device may not have knowledge about the differentCCATs. Thus, the wireless device may then receive the values of thedifferent CCATs from the AP. Once the wireless device has the knowledgeof the values of the different CCATs, the wireless device may startusing them for communicating with the AP.

Determining 230 whether the channel is busy or free may further based onQoS category of data that is currently being transmitted on the channelas discovered when determining 230 whether the channel is busy or free.

When the wireless device senses the channel, or radio resources, inorder to determine if the channel is busy or free, the wireless devicemight receive, or detect, signals or energy on the channel. If thesignals are traffic, and not noise, the wireless device may eitherdecode the signals, perform deep packet inspection or otherwise analysethe receive signals or energy in order to determine the QoS category ofdata that is currently being transmitted on the channel in the same, orsimilar, manner as the AP may do as described above.

The wireless device thus determines whether the channel is busy or freebased on the CCAT of the QoS category of the data to be transmitted tothe AP and also based on the QoS category of data that is currentlybeing transmitted on the channel.

In an example, the channel is determined to be free if the level of aQoS category of the data to be transmitted to the AP is of higherpriority than the level of the QoS category of data that is currentlybeing transmitted on the channel.

By determining the QoS category of data that is currently beingtransmitted on the channel, the wireless device may compare that QoScategory to the QoS category of the data to be transmitted to the AP.

As stated above, by increasing the CCAT for a certain QoS category, thetraffic of that access class has increased probability of accessing thechannel, but it comes at a risk of suffering from interference.Therefore the CCAT may e.g. only be increased for traffic types that arenot sensitive to losing packets (e.g. it may not be suitable for voiceand video but rather for best effort or background).

The wireless device may thus compare the QoS category of the data to betransmitted to the AP and QoS category of data that is currently beingtransmitted on the channel.

The channel may be determined to be free if the level of the QoScategory of the data to be transmitted to the AP is of higher prioritythan the level of the QoS category of data that is currently beingtransmitted on the channel. Merely as a non-limiting and simplifiedexample, assuming there are only two CCATs, a first CCAT for QoScategory related for speech, and the same first CCAT for QoS categoryrelated for video; and a second CCAT QoS category related for besteffort, and the same second CCAT for QoS category related forbackground. In this non-limiting and simplified example, data relatingto speech or video has higher priority than data relating to best effortor background. Thus, if the wireless device is to transmit speech orvideo to the AP and uses the first CCAT for determining if the channelis busy or free, and then detects traffic carrying data relating tobackground or best effort, the wireless device determines the channel tobe free and transmits its data to the AP.

However, in a more general, and not so simplified example, the wirelessdevice may compare the QoS category of the data to be transmitted to theAP and QoS category of data that is currently being transmitted on thechannel. In case there are more than two CCATs, e.g. four CCATs, CCAT_1,CCAT_2, CCAT_3 and CCAT_4. If the different CCATs have different values,then there can be different combinations of the CCAT of the data to betransmitted to the AP and the CCAT of the data that is currently beingtransmitted on the channel. Different combinations of different CCATsmay be associated with different rules regarding how the wireless deviceshould act for different combinations. The wireless device may thus,e.g. consult a lookup table comprising different rules for differentcombinations of CCATs. The different rules for different combinationsmay also reflect whether the CCAT is for the data to be transmitted tothe AP (own-QoS) or for the data that is currently being transmitted onthe channel (other-QoS). Consequently, a higher CCAT may be given whenthe own-QoS is higher than the other-QoS, but lower for the oppositecase.

Also for the method performed by the wireless device, the respective QoScategories may be associated with Access Categories.

As described above, there are four different QoS differentiations in theIEEE 802.11 standard, referred to as access categories. These categoriesare VO, VI, BE and BK. The method performed by the wireless device maybe employed by a wireless device operable in a network based on the IEEE802.11 standard, wherein these already defined access categories may beused. However, it shall be pointed out that the access categories may bedefined in other ways, e.g. when the wireless device is operable in anetwork based on another standard.

In addition to the CCAT, other parameters may be used in order tostatistically differentiate types of traffic, e.g. InterFrame Spacing,IFS, Contention Window size, CW size, which may be defined by a CW_minand a CW_max representing lowest and highest number respectively for thecontention window, Transmission Opportunity, TXOP, maximum allowed size.

Originally, data frames in 802.11 were sent using the DistributedCoordination Function, DCF. However, the DCF did not provide sufficientmeans for enabling QoS differentiation between different types oftraffic or between different associated wireless devices. The 802.11eamendment resolved this by introducing the Enhanced Distributed ChannelAccess, EDCA, by which a certain set of parameters could be adjusted insuch a way so that a certain type of traffic is handled with a differentpriority than another (in the statistical sense). Those parameters arethe IFS, CW size, and TXOP as described above.

Also as described above, in the 802.11 standard, four access categoriesare defined, VO, VI, BE, and BK. For each access category, there is aset of IFS, CW and TXOP limit values and all together, the values forthe four access categories are referred to as Enhanced DistributedChannel Access, EDCA, parameter set. The WLAN AP may advertise the EDCAparameter set via the EDCA Parameter set element, in a Beacon, ProbeResponse, Association Response or Re-association Response frames.Different QoS wireless devices (wireless devices that support the802.11e mechanisms) that are associated or are in process of associatingto an AP will use the EDCA parameters advertised by that AP for theuplink direction. In general the AP might choose to use different EDCAparameters for the downlink direction.

The channel access timing (i.e. priorities) for the different accesscategories, ACs, and also for non-QoS traffic is shown in FIG. 3B.

The EDCA parameter set has the format as illustrated in FIG. 3C. In thefigure, some exemplifying values are provided for the sake of clarity.It shall be pointed out that these values are merely examples and arenot to be understood as, or taken for, optimum, preferable or in otherway guiding values.

In an example, both the EDCA parameter set and the different CCATs fordifferent QoS categories may be used together to further increaseflexibility and efficiency for the communication between the AP and thewireless device. An example of using the EDCA parameter set and thedifferent CCATs for different QoS categories together is illustrated inFIG. 3D. It shall be pointed out that also these values in FIG. 3D aremerely examples and are not to be understood as, or taken for, optimum,preferable or in other way guiding values.

In FIG. 3D, the CCATs are exemplified as “exact” values, however, asdescribed above, the CCAT value comprise a range of values to beconsidered (e.g. CCAT_min and CCAT_max). In this way, a particularwireless device that applies the different CCATs for different QoScategories may have the liberty to adapt the CCAT based on a specificmechanism.

The different CCATs may be the signal detection threshold, an energydetection threshold, RX (receiver) sensitivity level, a combination ofthese, or all of them.

The CCAT may be communicated from the AP to the wireless device usingthe same mechanisms used to communicate the EDCA parameter petelement—it could be either broadcasted by the AP (i.e. the AP includesthe enhanced EDCA parameter set and the different CCATs in beaconframes), or unicasted to a particular wireless device, i.e. the APincludes the EDCA parameter set and the different CCATs either in proberesponse, Association or Reassociation Response or Channel UsageResponse.

In an example, the relative channel access of the different accesscategories may be measured by the AP or some central node, and then CCATvalues for different access categories may be updated to reach a certaindesired relative channel access distribution between the accesscategories. This desired distribution may in turn be dependent on somestatistics derived from the traffic, e.g. number of sessions ofdifferent type, the long-term average traffic volume for differentaccess categories.

Further, as described above, the AP and/or the wireless device may applythe CCAT of each QoS category based on the type of traffic it detects onthe channel and/or that it overhears from a neighbour BSS.

The access categories, ACs, video and voice have higher requirements onlatency and throughput hence should be protected from interference. Ifan AP or wireless device detects these types of traffic, the AP orwireless device should utilise lower CCAT values to avoid interferingthe ongoing transmission (as illustrated in an exemplifying manner inFIG. 3D).

In an example, the access category information may be included in a PHYheader so that an AP or wireless device may identify the type of trafficby reading the header. In another example, the real time traffic accesscategory information may be exchanged between APs so that correspondingCCAT may be configured in neighbour BSSs.

In yet another example, an AP or wireless device may determine the CCATsbased on the combination of transmission traffic types and sensedtraffic type. Comparing to the other two examples, this method mayprovide a higher degree of freedom in CCAT determination. An example ofCCAT values in such combination is given in FIG. 3E in an exemplifyingmanner.

Embodiments herein also relate to an AP in a WLAN for communicating witha wireless device, the WLAN employing contention based access for radioresources. The AP has the same technical features, objects andadvantages as the method performed by the AP. Hence, the AP will only bedescribed in brief in order to avoid unnecessary repetition.

Embodiments of such an AP will now be described with reference to FIGS.4 and 5. FIGS. 4 and 5 illustrate the AP 400, 500 being configured forusing a first CCAT for a first QoS category and at least a second CCATfor a second QoS category for communication with the wireless device.

The AP may be realised on implemented in various ways. A firstexemplifying realisation or implementation is illustrated in FIG. 4.FIG. 4 illustrates the AP comprising a processor 421 and memory 422, thememory comprising instructions, e.g. by means of a computer program 423,which when executed by the processor 421 causes the AP 400 to use afirst CCAT for a first QoS category and at least a second CCAT for asecond QoS category for communication with the wireless device.

FIG. 4 also illustrates the AP 400 comprising a memory 410. It shall bepointed out that FIG. 4 is merely an exemplifying illustration andmemory 410 may be optional, be a part of the memory 422 or be a furthermemory of the AP 400. The memory may for example comprise informationrelating to the AP 400, to statistics of operation of the AP 400, justto give a couple of illustrating examples. FIG. 4 further illustratesthe AP 400 comprising processing means 420, which comprises the memory422 and the processor 421. Still further, FIG. 4 illustrates the AP 400comprising a communication unit 430. The communication unit 430 maycomprise an interface through which the AP 400 communicates with othernodes or entities of the WLAN as well as other communication units. FIG.4 also illustrates the AP 400 comprising further functionality 440. Thefurther functionality 440 may comprise hardware of software necessaryfor the AP 400 to perform different tasks that are not disclosed herein.

An alternative exemplifying realisation, or implementation, of the AP isillustrated in FIG. 5. FIG. 5 illustrates the AP 500 comprising a usingunit 505 for using a first CCAT for a first QoS category and at least asecond CCAT for a second QoS category for communication with thewireless device.

FIG. 5 also illustrates the AP 500 comprising a determining unit 503 anda transmitting unit 505. These units may be optional and are thereforeillustrated having dotted lines.

In FIG. 5, the AP 500 is also illustrated comprising a communicationunit 501. Through this unit, the AP 500 is adapted to communicate withother nodes and/or entities in the WLAN. The communication unit 501 maycomprise more than one receiving arrangement. For example, thecommunication unit 501 may be connected to both a wire and an antenna,by means of which the AP 500 is enabled to communicate with other nodesand/or entities in the wireless communication network. Similarly, thecommunication unit 501 may comprise more than one transmittingarrangement, which in turn is connected to both a wire and an antenna,by means of which the AP 500 is enabled to communicate with other nodesand/or entities in the wireless communication network. The AP 500further comprises a memory 502 for storing data. Further, the AP 500 maycomprise a control or processing unit (not shown) which in turn isconnected to the different units 503-504. It shall be pointed out thatthis is merely an illustrative example and the AP 500 may comprise more,less or other units or modules which execute the functions of the AP 500in the same manner as the units illustrated in FIG. 5.

It should be noted that FIG. 5 merely illustrates various functionalunits in the AP 500 in a logical sense. The functions in practice may beimplemented using any suitable software and hardware means/circuits etc.Thus, the embodiments are generally not limited to the shown structuresof the AP 500 and the functional units. Hence, the previously describedexemplary embodiments may be realised in many ways. For example, oneembodiment includes a computer-readable medium having instructionsstored thereon that are executable by the control or processing unit forexecuting the method steps in the AP 500. The instructions executable bythe computing system and stored on the computer-readable medium performthe method steps of the AP 500 as set forth in the claims.

The method performed by the AP may have several advantages. One possibleadvantage is that the flexibility of the QoS framework is improvedand/or increased by introducing another degree of freedom to theparameters that can be adjusted in order to provide statisticaldifferentiation between different traffic types.

The AP may further be adapted for determining the first CCAT and/or thesecond CCAT for the first and second QoS category.

According to an embodiment, the AP may further be configured fortransmitting the first CCAT and/or the second CCAT for the first andsecond QoS category to the wireless device.

According to yet an embodiment, the AP may further be configured fordetermining of the first and/or second CCAT by determining respectiveintervals for the first and second CCATs within which the first and thesecond CCATs may vary.

According to still an embodiment, the AP may further be configured for,when using the determined first and/or second CCAT for communicationwith the wireless device: determining whether the channel is busy orfree using the CCAT for the QoS category of the data to be transmittedto the wireless device; and transmitting data to the wireless devicewhen the channel is free.

According to another embodiment, the AP may further be configured forthe determining of whether the channel is busy or free further based ona QoS category of data that is currently being transmitted on thechannel as discovered during the determining of whether the channel isbusy or free.

According to an embodiment, the channel is determined to be free if thelevel of the QoS category of the data to be transmitted to the wirelessdevice is of higher priority than the level of the QoS category of datathat is currently being transmitted on the channel.

According to yet an embodiment, the respective QoS categories areassociated with Access Categories.

According to still an embodiment, the AP may further be configured forupdating at least one of the CCATs and for transmitting the updated atleast one CCAT to the wireless device.

According to another embodiment, wherein the determined first and/orsecond CCAT is/are (i) specific for the wireless device, or (ii) commonfor all wireless devices communicating with the AP.

Embodiments herein also relate to a wireless device in a WLAN forcommunicating with an AP, the WLAN employing contention based access forradio resources. The wireless device has the same technical features,objects and advantages as the method performed by the wireless device.Hence, the wireless device will only be described in brief in order toavoid unnecessary repetition.

Embodiments of such a wireless device will now be described withreference to FIGS. 6 and 7. FIGS. 6 and 7 illustrate the wireless device600, 700 being configured for determining, a CCAT for a QoS category ofdata to be transmitted to the AP, wherein at least two different QoScategories are associated with different CCATs; for determining whetherthe channel is busy or free using the determined CCAT; and fortransmitting data to the AP when the channel is determined to be free.

The wireless device may be realised on implemented in various ways. Afirst exemplifying realisation or implementation is illustrated in FIG.6. FIG. 6 illustrates the wireless device comprising a processor 621 andmemory 622, the memory comprising instructions, e.g. by means of acomputer program 623, which when executed by the processor 621 causesthe wireless device 600 to determine, a CCAT for a QoS category of datato be transmitted to the AP, wherein at least two different QoScategories are associated with different CCATs; to determine whether thechannel is busy or free using the determined CCAT; and to transmit datato the AP when the channel is determined to be free.

FIG. 6 also illustrates the wireless device 600 comprising a memory 610.It shall be pointed out that FIG. 6 is merely an exemplifyingillustration and memory 610 may be optional, be a part of the memory 622or be a further memory of the wireless device 600. The memory may forexample comprise information relating to the wireless device 600, tostatistics of operation of the wireless device 600, just to give acouple of illustrating examples. FIG. 6 further illustrates the wirelessdevice 600 comprising processing means 620, which comprises the memory622 and the processor 621. Still further, FIG. 6 illustrates thewireless device 600 comprising a communication unit 630. Thecommunication unit 630 may comprise an interface through which thewireless device 600 communicates with other nodes or entities of theWLAN as well as other communication units. FIG. 6 also illustrates thewireless device 600 comprising further functionality 640. The furtherfunctionality 640 may comprise hardware of software necessary for thewireless device 600 to perform different tasks that are not disclosedherein.

An alternative exemplifying realisation, or implementation, of thewireless device is illustrated in FIG. 7. FIG. 7 illustrates thewireless device 700 comprising a determining unit 703 for determining aCCAT for a QoS category of data to be transmitted to the AP, wherein atleast two different QoS categories are associated with different CCATs;and for determining whether the channel is busy or free using thedetermined CCAT. FIG. 7 also illustrates the wireless device 700comprising a transmitting unit 704 for transmitting data to the AP whenthe channel is determined to be free.

In FIG. 7, the wireless device 700 is also illustrated comprising acommunication unit 701. Through this unit, the wireless device 700 isadapted to communicate with other nodes and/or entities in the WLAN. Thecommunication unit 701 may comprise more than one receiving arrangement.For example, the communication unit 701 may be connected to both a wireand an antenna, by means of which the wireless device 700 is enabled tocommunicate with other nodes and/or entities in the wirelesscommunication network. Similarly, the communication unit 701 maycomprise more than one transmitting arrangement, which in turn isconnected to both a wire and an antenna, by means of which the wirelessdevice 700 is enabled to communicate with other nodes and/or entities inthe wireless communication network. The wireless device 700 furthercomprises a memory 702 for storing data. Further, the wireless device700 may comprise a control or processing unit (not shown) which in turnis connected to the different units 703-704. It shall be pointed outthat this is merely an illustrative example and the wireless device 700may comprise more, less or other units or modules which execute thefunctions of the wireless device 700 in the same manner as the unitsillustrated in FIG. 7.

It should be noted that FIG. 7 merely illustrates various functionalunits in the wireless device 700 in a logical sense. The functions inpractice may be implemented using any suitable software and hardwaremeans/circuits etc. Thus, the embodiments are generally not limited tothe shown structures of the wireless device 700 and the functionalunits. Hence, the previously described exemplary embodiments may berealised in many ways. For example, one embodiment includes acomputer-readable medium having instructions stored thereon that areexecutable by the control or processing unit for executing the methodsteps in the wireless device 700. The instructions executable by thecomputing system and stored on the computer-readable medium perform themethod steps of the wireless device 700 as set forth in the claims.

The wireless device has the same possible advantages as the methodperformed by the wireless device. One possible advantage is that theflexibility of the QoS framework is improved and/or increased byintroducing another degree of freedom to the parameters that can beadjusted in order to provide statistical differentiation betweendifferent traffic types.

According to an embodiment, the wireless device 600, 700 may further beconfigured for receiving, from the AP, a first CCAT for a first QoScategory and at least a second CCAT for a second QoS category, wherebythe first and second CCAT are different.

According to yet an embodiment, the wireless device 600, 700 may furtherbe configured for determining whether the channel is busy or freefurther based on QoS category of data that is currently beingtransmitted on the channel as discovered when determining 230 whetherthe channel is busy or free.

According to still an embodiment, the channel is determined to be freeif the level of a QoS category of the data to be transmitted to the APis of higher priority than the level of the QoS category of data that iscurrently being transmitted on the channel.

According to another embodiment, the respective QoS categories areassociated with Access Categories.

FIG. 8 schematically shows an embodiment of an arrangement 800 in an AP500. Comprised in the arrangement 800 in the AP 500 are here aprocessing unit 806, e.g. with a Digital Signal Processor, DSP. Theprocessing unit 806 may be a single unit or a plurality of units toperform different actions of procedures described herein. Thearrangement 800 of the AP 500 may also comprise an input unit 802 forreceiving signals from other entities, and an output unit 804 forproviding signal(s) to other entities. The input unit and the outputunit may be arranged as an integrated entity or as illustrated in theexample of FIG. 5, as one or more interfaces 501.

Furthermore, the arrangement in the AP 500 comprises at least onecomputer program product 808 in the form of a non-volatile memory, e.g.an Electrically Erasable Programmable Read-Only Memory, EEPROM, a flashmemory and a hard drive. The computer program product 808 comprises acomputer program 810, which comprises code means, which when executed inthe processing unit 806 in the arrangement 800 in the AP 500 causes theAP to perform the actions e.g. of the procedure described earlier inconjunction with FIGS. 1A-1C.

The computer program 810 may be configured as a computer program codestructured in computer program modules 810 a-810 e. Hence, in anexemplifying embodiment, the code means in the computer program of thearrangement 800 in the AP comprises a using unit, or module, for using afirst CCAT for a first QoS category and at least a second CCAT for asecond QoS category for communication with the wireless device.

The computer program modules could essentially perform the actions ofthe flow illustrated in FIGS. 1A-1C, to emulate the AP 500. In otherwords, when the different computer program modules are executed in theprocessing unit 806, they may correspond to the unit 505 of FIG. 5.

FIG. 9 schematically shows an embodiment of a wireless device 900.Comprised in the wireless device 900 are here a processing unit 906,e.g. with a Digital Signal Processor. The processing unit 906 may be asingle unit or a plurality of units to perform different actions ofprocedures described herein. The wireless device 900 may also comprisean input unit 902 for receiving signals from other entities, and anoutput unit 904 for providing signal(s) to other entities. The inputunit and the output unit may be arranged as an integrated entity or asillustrated in the example of FIG. 7, as one or more interfaces 701.

Furthermore, the wireless device 900 comprises at least one computerprogram product 908 in the form of a non-volatile memory, e.g. anElectrically Erasable Programmable Read-Only Memory, EEPROM, a flashmemory and a hard drive. The computer program product 908 comprises acomputer program 910, which comprises code means, which when executed inthe processing unit 906 in the arrangement 900 in the wireless devicecauses the wireless device to perform the actions e.g. of the proceduredescribed earlier in conjunction with FIGS. 2A and 2B.

The computer program 910 may be configured as a computer program codestructured in computer program modules 910 a-910 e. Hence, in anexemplifying embodiment, the code means in the computer program of thearrangement 900 in the wireless device comprises a determining unit, ormodule, for determining, a CCAT for a QoS category of data to betransmitted to the AP, wherein at least two different QoS categories areassociated with different CCATs; for determining whether the channel isbusy or free using the determined CCAT. The computer program furthercomprises a transmitting unit, or module, for transmitting data to theAP when the channel is determined to be free.

The computer program modules could essentially perform the actions ofthe flow illustrated in FIGS. 2A and 2B, to emulate the wireless device700. In other words, when the different computer program modules areexecuted in the processing unit 906, they may correspond to the units703-704 of FIG. 7.

Although the code means in the respective embodiments disclosed above inconjunction with FIGS. 5 and 7 are implemented as computer programmodules which when executed in the respective processing unit causes theAP and the wireless device respectively to perform the actions describedabove in the conjunction with Figures mentioned above, at least one ofthe code means may in alternative embodiments be implemented at leastpartly as hardware circuits.

The processor may be a single Central Processing Unit, CPU, but couldalso comprise two or more processing units. For example, the processormay include general purpose microprocessors; instruction set processorsand/or related chips sets and/or special purpose microprocessors such asApplication Specific Integrated Circuits, ASICs. The processor may alsocomprise board memory for caching purposes. The computer program may becarried by a computer program product connected to the processor. Thecomputer program product may comprise a computer readable medium onwhich the computer program is stored. For example, the computer programproduct may be a flash memory, a Random-Access Memory RAM, Read-OnlyMemory, ROM, or an EEPROM, and the computer program modules describedabove could in alternative embodiments be distributed on differentcomputer program products in the form of memories within the AP and thewireless device respectively.

It is to be understood that the choice of interacting units, as well asthe naming of the units within this disclosure are only for exemplifyingpurpose, and nodes suitable to execute any of the methods describedabove may be configured in a plurality of alternative ways in order tobe able to execute the suggested procedure actions.

It should also be noted that the units described in this disclosure areto be regarded as logical entities and not with necessity as separatephysical entities.

While the embodiments have been described in terms of severalembodiments, it is contemplated that alternatives, modifications,permutations and equivalents thereof will become apparent upon readingof the specifications and study of the drawings. It is thereforeintended that the following appended claims include such alternatives,modifications, permutations and equivalents as fall within the scope ofthe embodiments and defined by the pending claims.

The invention claimed is:
 1. A method for communicating with a wireless device in a Wireless Local Area Network (WLAN) employing contention-based access to a channel, the method comprising: determining one or more Clear Channel Assessment Thresholds (CCATs) for data to be transmitted to the wireless device, wherein each CCAT is associated with a particular Quality of Service (QoS) category of the data; determining whether the channel is busy or free based on the determined one or more CCATs and based on signals or energy detected on the channel; and based on determining that the channel is free, transmitting the data to the wireless device.
 2. The method of claim 1, wherein determining whether the channel is busy or free comprises comparing the signals or energy detected on the channel to the respective one or more CCATs.
 3. The method of claim 1, further comprising transmitting the determined one or more CCATs to the wireless device.
 4. The method of claim 1, wherein determining the one or more CCATs comprises determining intervals for the respective CCATs within which the respective CCATs can be adjusted.
 5. The method of claim 4, further comprising, prior to determining whether the channel is free or busy, adjusting the determined one or more CCATs within their respective intervals based on one or more of the following with respect to the wireless device: a measured received signal strength (RSS), and block error rate (BLER) of received packets.
 6. The method of claim 1, wherein determining whether the channel is busy or free comprises: detecting, within the signals or energy, a QoS category of further data being transmitted on the channel; and comparing a priority level associated with the QoS category of the data to be transmitted to a further priority level associated with the QoS category of the further data that is being transmitted.
 7. The method of claim 6, wherein the channel is determined to be free if the priority level is of higher priority than the further priority level.
 8. The method of claim 6, wherein the data is transmitted to the wireless device while the further data is being transmitted.
 9. The method of claim 1, further comprising updating at least one of the CCATs and transmitting the updated at least one CCAT to the wireless device.
 10. A method performed by a wireless device for communicating with an Access Point (AP) in a Wireless Local Area Network (WLAN) employing contention-based access to a channel, the method comprising: determining one or more Clear Channel Assessment Thresholds (CCATs) for data to be transmitted to the AP, wherein each CCAT is associated with a particular Quality of Service (QoS) category of the data; determining whether the channel is busy or free based on the determined one or more CCATs and based on signals or energy detected on the channel; and based on determining that the channel is free, transmitting the data to the AP.
 11. The method of claim 10, wherein determining whether the channel is busy or free comprises comparing the signals or energy detected on the channel to the respective one or more CCATs.
 12. The method of claim 10, determining the one or more CCATs comprises receiving the one or more CCATs from the AP.
 13. The method of claim 10, wherein determining whether the channel is busy or free comprises: detecting, within the signals or energy, a QoS category of further data being transmitted on the channel; and comparing a priority level associated with the QoS category of the data to be transmitted to a further priority level associated with the QoS category of the further data that is being transmitted.
 14. The method of claim 13, wherein the channel is determined to be free if the priority level is of higher priority than the further priority level.
 15. The method of claim 13, wherein the data is transmitted to the AP while the further data is being transmitted.
 16. An Access Point (AP) arranged to communicate with a wireless device in a Wireless Local Area Network (WLAN) employing contention-based access for radio resources, the AP comprising: at least one processor; and at least one memory storing computer-executable instructions that, when executed by the at least one processor, configure the AP to: determine one or more Clear Channel Assessment Thresholds (CCATs) for data to be transmitted to the wireless device, wherein each CCAT is associated with a particular Quality of Service (QoS) category of the data; determine whether the channel is busy or free based on the determined one or more CCATs and based on signals or energy detected on the channel; and based on determining that the channel is free, transmit the data to the wireless device.
 17. The AP of claim 16, wherein execution of the instructions configures the AP to determine the one or more CCATs based on determining intervals for the respective CCATs within which the respective CCATs can be adjusted.
 18. The AP of claim 17, wherein execution of the instructions further configures the AP to, prior to determining whether the channel is free or busy, adjust the determined one or more CCATs within their respective intervals based on one or more of the following with respect to the wireless device: a measured received signal strength (RSS), and block error rate (BLER) of received packets.
 19. The AP of claim 16, wherein execution of the instructions configures the AP to determine whether the channel is busy or free based on: detecting, within the signals or energy, a QoS category of further data being transmitted on the channel; and comparing a priority level associated with the QoS category of the data to be transmitted to a further priority level associated with the QoS category of the further data that is being transmitted.
 20. The AP of claim 19, wherein execution of the instructions configures the AP to transmit the data to the wireless device while the further data is being transmitted.
 21. A wireless device arranged to communicate with an Access Point (AP) in a Wireless Local Area Network (WLAN) employing contention-based access of a channel to the AP, the wireless device comprising: at least one processor; and at least one memory storing computer-executable instructions that, when executed by the at least one processor, configure the wireless device to perform operations corresponding to the method of claim
 10. 22. The wireless device of claim 21, wherein execution of the instructions configures the wireless device to determine whether the channel is busy or free based on: detecting, within the signals or energy, a QoS category of further data being transmitted on the channel; and comparing a priority level associated with the QoS category of the data to be transmitted to a further priority level associated with the QoS category of the further data that is currently being transmitted.
 23. The wireless device of claim 22, wherein execution of the instructions configures the wireless device to transmit the data to the AP while the further data is being transmitted. 